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authorRonald S. Bultje <rsbultje@gmail.com>2011-12-16 00:03:54 +0000
committerMans Rullgard <mans@mansr.com>2011-12-17 18:36:20 +0000
commitbe1bafc303a77fa9ca5a99e36a65d5765012d3f4 (patch)
tree6e7daa2b038cb79f72f8d0fc4ef04756eebad93d /libavcodec/snowdec.c
parent5d8122db5c0b537c4d2c3352b4c89cb92f865bc2 (diff)
downloadffmpeg-be1bafc303a77fa9ca5a99e36a65d5765012d3f4.tar.gz
swscale: fix overflows in output of RGB48 pixels.
For certain types of filters where the intermediate sum of coefficients can go above the fixed-point equivalent of 1.0 in the middle of a filter, the sum of a 31-bit calculation can overflow in both directions and can thus not be represented in a 32-bit signed or unsigned integer. To work around this, we subtract 0x40000000 from a signed integer base, so that we're halfway signed/unsigned, which makes it fit even if it overflows. After the filter finishes, we add the scaled bias back after a shift. We use the same trick for 16-bit bpc YUV output routines. Signed-off-by: Mans Rullgard <mans@mansr.com>
Diffstat (limited to 'libavcodec/snowdec.c')
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